Circular knitting machine for hosiery or the like, with device for actuating the knockover sinkers

ABSTRACT

A circular knitting machine for hosiery or the like, with a device for actuating the knockover sinkers, comprising a sinker cover, arranged in an upward region and coaxially to the sinker ring and supporting at least one cam and one complementary cam arranged outside the cam with respect to the cylinder axis, the cam and the complementary cam forming path portions running around the cylinder axis engageable by a heel of the knockover sinkers to actuate movement thereof along a radial direction, a first actuation varying angular position of the sinker cover, and a second actuation varying movement of the complementary cam.

The present invention relates to a circular knitting machine for hosieryor the like, with device for actuating the knockover sinkers.

BACKGROUND OF THE INVENTION

As is known, circular hosiery knitting machines, particularlysingle-cylinder circular machines, have knockover sinkers located insideradial slots of an appropriately provided support known as sinker ring,which is monolithically associated with the needle cylinder proximate toits upper end.

The knockover sinkers are staggered with respect to the needles, so thateach sinker lies between two contiguous needles, and are actuated,during the rotation of the needle cylinder about its own axis, with areciprocating motion along a radial direction with respect to the needlecylinder.

More particularly, the knockover sinkers are moved away from the axis ofthe needle cylinder when the needles, after engaging the thread, starttheir descent to form new loops of knitting, so that the region of thethread or threads between two contiguous loops rests on the upperportion of the sinkers, which is usually flat and known as knockoverplane, while the loops formed previously are knocked over, i.e.,released by the corresponding needle. After knocking over the old loops,while the needles start a new upward motion, the sinkers are movedtoward the axis of the needle cylinder in order to engage the new loopsby means of a hook that lies above the knockover plane, so as to retainand tension the loops against the shank of the needles. This retentionagainst the shank of the needles also has the effect of assuredlyopening the latch located proximate to the hook of the needles, whilethe tensioning, particularly after forming the new loop, shapes the partof said loop produced by the sinker.

The movement of the knockover sinkers along a radial direction withrespect to the needle cylinder toward and away from the axis of saidneedle cylinder is achieved by means of an annular cam, which liesaround the axis of the needle cylinder. The movement toward the axis ofthe needle cylinder, particularly after forming the new loop, isassisted by a complementary cam, and said cam and complementary cam areassociated with a sinker cover which lies above the sinker ring and issupported by the supporting structure of the machine.

At least one complementary cam for each feed or drop of the machine isgenerally provided.

The annular cam and the complementary cams lie around the axis of theneedle cylinder and trace a path with portions that move toward the axisof the needle cylinder and portions that move away from it; said path isengaged by a heel of the sinkers, which protrudes upward from the sinkerring, when the needle cylinder is actuated so as to rotate about its ownaxis with respect to the supporting structure of the machine andtherefore with respect to the cover of the sinkers.

In the production of knitted articles it is necessary to be able toadvance or delay the movement of the sinkers and to vary the extent ofthe movement of the sinkers away from the axis of the needle cylinder,in order to be able to obtain high-quality articles by perfectlybalancing the part of the loop that is formed by the needle, which canvary in the row, with the part of loop that is formed by the sinker.

To meet these requirements, the cover of the sinkers is supported sothat it can rotate about the axis of the needle cylinder, and thecomplementary cams can move with respect to the sinker cover toward oraway from the axis of the needle cylinder; there are also firstactuation means, which act on the sinker cover in order to turn it aboutthe axis of the needle cylinder through a preset angle, and secondactuation means, which act on command on the complementary cams in orderto vary their position with respect to the sinker cover along a radialdirection with respect to the axis of the needle cylinder.

In many modern hosiery knitting machines, the first actuation means andthe second actuation means are constituted by a first step motor and bya second step motor, which are respectively connected to the sinkercover and to the complementary cams by way of a gear transmission.

The first step motor is usually supported by a fixed structure, whilethe second step motor is generally mounted on the sinker cover.

However, the gear transmission causes problems and drawbacks.

More particularly, the adoption of a gear transmission, which allows tohave an adequately low contrast torque on the motor shaft, requires arelatively large number of components, with consequent production costs.

Moreover, the plays in the meshing of the teeth of the various gearscauses instability in the angular position of the sinker cover aroundthe axis of the needle cylinder.

The mounting of the step motor for varying the position of thecomplementary cams on the sinker cover causes an imbalance andinstability of said cover that can cause work defects and poor productquality.

SUMMARY OF THE INVENTION

The aim of the present invention is to solve the problems mentionedabove, by providing a circular knitting machine for hosiery or the like,with a device for actuating the knockover sinkers, that allows toachieve high precision in adjusting the angular position of the sinkercover and/or the movement of the complementary cams along a radialdirection with respect to the axis of the needle cylinder.

Within this aim, an object of the invention is to provide a device foractuating the knockover sinkers that can be produced with a reducednumber of components.

Another object of the invention is to provide a device for actuating theknockover sinkers that has high precision and stability in operation.

This aim and these and other objects that will become better apparenthereinafter, are achieved by a circular knitting machine for hosiery orthe like, with a device for actuating the knockover sinkers, comprising:

-   a needle cylinder, arranged so that its axis is substantially    vertical and can be actuated so as to rotate about said axis;-   a sinker ring, rigidly coupled to said needle cylinder in rotation    about its axis and arranged coaxially to the needle cylinder    proximate to its upper end, said sinker ring supporting a plurality    of knockover sinkers, which can move radially with respect to the    needle cylinder and the sinker ring;-   a sinker cover, arranged in an upward region and coaxially with    respect to said sinker ring and supporting at least one cam and at    least one complementary cam, which is arranged outside said cam with    respect to the axis of the needle cylinder; said cam and said    complementary cam forming portions of a path that runs around the    axis of the needle cylinder and can be engaged by a heel of the    knockover sinkers in order to actuate the movement of the knockover    sinkers along a radial direction with respect to the needle cylinder    when the needle cylinder rotates about its own axis with respect to    said sinker cover, said cam and said complementary cam, said    complementary cam being movable with respect to said sinker cover    along a direction that is substantially radial to the axis of the    needle cylinder;-   first actuation means, acting on said sinker cover to turn it about    the axis of the needle cylinder;-   second actuation means, adapted to vary the extent of the movement    of said complementary cam along said substantially radial direction    with respect to said axis of the needle cylinder;    characterized in that said first actuation means and/or said second    actuation means comprise an electric motor, which is connected to    said sinker cover and/or to said at least one complementary cam by    way of a cam transmission.

BRIEF DESCRIPTION OF THE DRAWINGS

Further characteristics and advantages of the invention will becomebetter apparent from the description of an embodiment of the machinewith device for actuating the knockover sinkers according to theinvention, illustrated only by way of non-limitative example in theaccompanying drawings, wherein:

FIG. 1 is a schematic top plan view of a portion of the sinker ring;

FIG. 2 is an enlarged-scale sectional view of FIG. 1, taken along theline II—II;

FIG. 3 is an enlarged-scale sectional view of FIG. 1, taken along theline III—III;

FIG. 4 is an enlarged-scale sectional view of FIG. 1, taken along theline IV—IV, with some details omitted for the sake of simplicity;

FIG. 5 is an enlarged-scale sectional view of FIG. 1, taken along theline V—V;

FIG. 6 is an enlarged-scale sectional view of FIG. 1, taken along theline VI—VI.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

With reference to the figures, the circular machine with device foractuating the knockover sinkers comprises, in a per se known manner, aneedle cylinder, which is arranged so that its axis 2 a is substantiallyvertical and can be actuated with a rotary motion about said axis 2 awith respect to the supporting structure of the machine.

The machine comprises a sinker ring 3, which is fixed coaxially to theneedle cylinder proximate to its upper end. The sinker ring 3 ismonolithically coupled to the needle cylinder in its rotation about itsaxis 2 a with respect to the supporting structure of the machine.

The sinker ring 3 has, in a per se known manner, a plurality of radialslots 4, which are open upward; each slot accommodates a knockoversinker 5, which can slide radially with respect to the needle cylinderinside the corresponding slot 4. Each knockover sinker 5 has a heel 5 a,which protrudes upward from the corresponding slot 4, and above thesinker ring 3 there is a sinker cover 6, which is arranged coaxially tothe sinker ring 3 and supports at least one cam 7 and at least onecomplementary cam, which is arranged externally with respect to the cam7 relative to the axis 2 a of the needle cylinder.

In the illustrated embodiment, which relates to a circular knittingmachine with four feeds, there is a single annular cam 7 and there arethree complementary cams 8, 9 and 10 for each feed of the machine; saidcams are substantially shaped like annular sectors.

The cam 7 and the complementary cams 8–10 form portions of a path thatlies around the axis 2 a of the needle cylinder and can be engaged bythe heel 5 a of the knockover sinkers 5 in order to actuate the movementof the knockover sinkers 5 along a radial direction with respect to theaxis 2 a of the needle cylinder when the needle cylinder rotates aboutits own axis 2 a with respect to the sinker cover 6, the cam 7 and thecomplementary cams 8–10.

The machine further comprises first actuation means, which act on thesinker cover 6 to produce, when required, its rotation about the axis 2a of the needle cylinder, and second actuation means, which are adaptedto vary the extent of the movement of the complementary cams 8–10 alonga radial direction with respect to the axis 2 a.

More particularly, the sinker cover 6 is substantially composed of anupper ring 11 and a lower ring 12, whose axes coincide with the axis 2a.

The lower ring 12 is locked axially and radially on the sinker ring 3,as shown in particular in FIG. 2, but can rotate with respect to saidring about the axis 2 a. To allow and facilitate this rotation, bearings13 are interposed between the lower ring 12 and the sinker ring 3.

The upper ring 11 is supported by the lower ring 12, so as to allowrotation about the axis 2 a, by way of bearings 14, as shown in FIG. 3.Furthermore, the upper ring 11 is locked axially and radially on thelower ring 12, as shown in particular in FIG. 4, which shows that thereare additional bearings 15 between the upper ring 11 and the lower ring12.

The cam 7 can be provided monolithically and be fixed to the lower faceof the upper ring 11, or can be formed by a number of parts connected tothe lower face of the upper ring 11, with an annular shape provided withthe typical contoured regions proximate to the feeds or drops of themachine in order to produce the required movement of the sinkers towardand away from the axis 2 a of the needle cylinder.

The complementary cams 8–10 also are connected to the lower face of theupper ring 11, but are fixed to screws 16, which are slidingly coupledto appropriate slots 17 formed in the upper ring 11, so as to be able tomove along a radial direction with respect to the axis 2 a.

Preferably, the movement of the complementary cams 8–10 away from theaxis 2 a is contrasted by elastic means, which in the illustratedembodiment are constituted by an annular spring 18, which is arranged ina circular fashion around the axis 2 a and surrounds all of thecomplementary cams 8–10.

The lower ring 12 supports roller-shaped locators 20, which face theopposite side of the complementary cams 8–10 with respect to the cam 7and are designed to limit the movement of the complementary cams 8–10away from the cam 7 due to the force that the knitted fabric dischargesonto the sinkers 5, overcoming the elastic reaction of the annularspring 18.

The side of the complementary cams 8–10 that is designed to engage thelocators 20 is conveniently provided with a contoured profile so as tovary the distance between the locators 20 and the complementary cams8–10 when the angular position of the lower ring 12 around the axis 2 achanges with respect to the upper ring 11.

The first actuation means comprise a first electric motor 21, preferablya step motor, which is supported by a fixed structure 50 and is providedwith an output shaft that is orientated so that its axis is parallel tothe axis 2 a and on which a first actuation cam 22 is keyed; saidactuation cam is coupled to at least one cam follower, which isconnected to the upper ring 11.

Preferably, there are two cam followers 23 a and 23 b, constituted byrollers or bearings, which are connected to the upper ring 11 and arearranged so as to provide a bilateral coupling to the first actuationcam 22; said coupling can optionally be preloaded.

The second actuation means comprise a second electric motor, preferablya step motor, designated by the reference numeral 24, which is alsoconveniently supported by a fixed structure 50 and is provided with anoutput shaft, which is orientated so that its axis is parallel to theaxis 2 a and on which a second actuation cam 25 is keyed; said secondactuation cam is coupled to at least one cam follower connected to thelower ring 12.

Preferably, in this case also, there are two cam followers 26 a and 26b, constituted by rollers or bearings, which are connected to the lowerring 12 and are arranged so as to provide a bilateral coupling to thesecond actuation cam 25; said coupling can optionally be preloaded.

The portions of the profile of the actuation cams 22 and 25 thatcorrespond to the work angle of the actuation cams are complementary, soas to allow a transmission of motion from the actuation cams 22 and 25to the upper ring 11 and to the lower ring 12 that is practically freefrom play.

Moreover, the profile of the actuation cams 22 and 25 is preferablyprovided so as to establish a linear relationship between the rotationof the actuation cams 22 and 25 and the rotation of the upper ring 11and of the lower ring 12 respectively. This refinement allows tosimplify the programs for actuating and controlling the rotation of theupper ring 11 and of the lower ring 12.

Conveniently, sensing means are provided for sensing the rotation of theupper ring 11 and of the lower ring 12 about the axis 2 a.

Said sensing means can be constituted by known kinds of sensor, such asfor example encoders, for detecting the angular position of theactuation cams 22 and 25, or the angular position of the rings 11 and 12about the respective rotation axes. FIG. 6 illustrates, merely by way ofexample, a sensor 27 for controlling the rotation of the secondactuation cam 25.

Operation of the machine as regards the sinker actuation device is asfollows.

The actuation of the needle cylinder about its own axis 2 a andtherefore about the sinker ring 5 causes the heel 5 a of the sinkers 5to follow the path determined by the cam 7 and by the complementary cams8–10. The shape of this path causes, or allows, a movement of thesinkers 5 toward or away from the axis 2 a in order to meet the variouswork requirements.

When one wishes solely to advance or delay the movement of the sinkers 5with respect to the feeds or drops of the machine, both the first stepmotor 21 and the second step motor 24 are actuated; by means of thefirst actuation cam 22 and the second actuation cam 25, said motorscause the mutually rigid rotation of the upper ring 11 and of the lowerring 12 about the axis 2 a of the needle cylinder through a presetangle.

When instead one wishes to vary only the extent of the movement awayfrom the axis 2 a allowed to the sinkers 5 by the complementary cams8–10, the second step motor 24 is actuated; said motor, by causing therotation of the second actuation cam 25, moves the locators 20 toward oraway from the complementary cams 8–10.

In practice it has been found that the device according to the inventionfully achieves the intended aim, since it allows to obtain, with areduced number of components, high precision in adjusting the angularposition of the sinker cover and/or the position of the complementarycams along a radial direction with respect to the axis of the needlecylinder.

Another advantage, which arises from the adoption of a cam transmissioninstead of a gear transmission, is that it is possible to use the motorsthat actuate said cams with a lower rotation rate and therefore in amore advantageous region of their characteristic curve in which theavailable torque is higher for equal dimensions.

The machine with the device thus conceived is susceptible of numerousmodifications and variations, all of which are within the scope of theappended claims; all the details may further be replaced with othertechnically equivalent elements.

In practice, the materials used, as well as the dimensions, may be anyaccording to requirements and to the state of the art.

The disclosures in Italian Patent Application No. MI2002A001116 fromwhich this application claims priority are incorporated herein byreference.

1. A circular knitting machine for hosiery, with a device for actuatingthe knockover sinkers, comprising: a needle cylinder, arranged with anaxis thereof substantially vertical, said needle cylinder beingactuatable so as to rotate about said axis; a sinker ring, rigidlycoupled to said needle cylinder in rotation about said axis and arrangedcoaxially to the needle cylinder proximate to an upper end thereof, saidsinker ring being provided with a plurality of knockover sinkerssupported thereat, which are radially movable with respect to the needlecylinder and the sinker ring; a sinker cover composed of an upper ringand a lower ring and arranged in an upward region and coaxially withrespect to said sinker ring with supporting thereat at least one cam andat least one complementary can, which is arranged outside said at leastone cam with respect to the axis of the needle cylinder; said at leastone cam and said complementary cam forming portions of a path that runsround the axis of the needle cylinder and is engageable by a heel of theknockover sinkers in order to actuate movement of the knockover sinkersalong a radial direction with respect to the needle cylinder when theneedle cylinder rotates about said axis with respect to said sinkercover, said at least one cam and said complementary cam, saidcomplementary cam being movable with respect to said sinker cover alonga direction that is substantially radial to the axis of the needlecylinder; first actuation means, acting on said sinker cover to turn thesinker cover about said axis of the needle cylinder; second actuationmeans, adapted to vary a movement extent of said complementary cam alongsaid substantially radial direction with respect to said axis of theneedle cylinder; wherein said first actuation means comprises a firstelectric motor which is supported by a fixed structure and is providedwith an output shaft to which a first actuation cam is keyed, saidactuation cam being coupled to a pair of cam followers, which areconnected to said upper ring of the sinker cover and are arranged so asto provide a bilateral and preloadable coupling with a profile of saidfirst actuation cam.
 2. The machine according to claim 1, wherein saidupper ring supports said cam and said at least one complementary cam;said complementary cam being movable with respect to said upper ringalong said substantially radial direction with respect to the axis ofthe needle cylinder; said lower ring being arranged in a downward regionand coaxially with respect to said upper ring and having locatorssupported thereon, which face an opposite side of said complementary camthat is opposite with respect to a side that can engage the heel of thesinkers and are adapted to limit the movement of said complementary camalong said radial direction away from the axis of the needle cylinder.3. The machine according to claim 1, comprising elastic means thatcontrast movement of said complementary cam away from the axis of theneedle cylinder.
 4. The machine according to claim 2, wherein saidcomplementary cam has, on said opposite side thereof a profile that canengage said locators and is shaped so as to vary a distance of saidprofile from said locators when an angular position of said lower ringwith respect to said upper ring varies.
 5. The machine according toclaim 2, wherein said second actuation means comprise a second electricmotor, which is supported by a fixed structure and is provided with anoutput shaft with a second actuation cam keyed thereon, said secondactuation cam having coupled thereto at least one cam follower which isconnected to said lower ring of the sinker cover.
 6. The machineaccording to claim 5, comprising a pair of cam followers, which areconnected to said lower ring to which said second actuation cam iscoupled, said pair of cam followers being arranged so as to provide abilateral and preloadable coupling to the profile of said secondactuation cam.
 7. The machine according to claim 6, wherein said firstactuation cam and/or said second actuation cam are provided so as torotate about an axis that is parallel to the axis of the needlecylinder.
 8. The machine according to claim 7, wherein profile portionsof said first actuation cam and/or of said second actuation cam areshaped complementarily and are coupled, respectively, to said pairs ofcam followers.
 9. The machine according to claim 5, wherein said firstand second electric motor of the actuation means is constituted by astep motor.
 10. The machine according to claim 8, comprising sensingmeans for sensing rotation of said first actuation cam and/or of saidsecond actuation cam about axis thereof.
 11. The machine according toclaim 10, comprising sensing means for sensing rotation of said upperring and/or of said lower ring of the sinker cover about the axis of theneedle cylinder.
 12. The machine according to claim 8, wherein theprofile of said first actuation cam and/or of said second actuation camis shaped so as to determine a linear relationship between a rotation ofsaid first actuation cam and a rotation of said upper ring of the sinkercover and/or between a rotation of said second actuation cam and arotation of said lower ring of the sinker cover.
 13. A circular knittingmachine for hosiery, with a device for actuating the knockover sinkers,comprising: a needle cylinder, arranged with an axis thereofsubstantially vertical, said needle cylinder being actuatable so as torotate about said axis; a sinker ring, rigidly coupled to said needlecylinder in rotation about said axis and arranged coaxially to theneedle cylinder proximate to an upper end thereof, said sinker ringbeing provided with a plurality of knockover sinkers supported thereat,which are radially movable with respect to the needle cylinder and thesinker ring; a sinker cover composed of an upper ring and a lower ringand arranged in an upward region and coaxially with respect to saidsinker ring with supporting thereat at least one cam and at least onecomplementary cam, which is arranged outside said at least one cam withrespect to the axis of the needle cylinder; said at least one cam andsaid complementary cam forming portions of a path that runs around theaxis of the needle cylinder and is engageable by a heel of the knockoversinkers in order to actuate movement of the knockover sinkers along aradial direction with respect to the needle cylinder when the needlecylinder rotates about said axis with respect to said sinker cover, saidat least one cam and said complementary cam, said complementary cambeing movable with respect to said sinker cover along a direction thatis substantially radial to the axis of the needle cylinder; firstactuation means, acting on said sinker cover to turn the sinker coverabout said axis of the needle cylinder; second actuation means, adaptedto vary a movement extent of said complementary cam along saidsubstantially radial direction with respect to said axis of the needlecylinder; wherein said second actuation means comprise a second electricmotor, which is supported by a fixed structure and is provided with anoutput shaft with a second actuation cam keyed thereon, said secondactuation cam having coupled thereto a pair of cam followers, which areconnected to said lower ring of the sinker cover to which said secondactuation cam is coupled, said pair of cam followers being arranged soas to provide a bilateral and preloadable coupling to the profile ofsaid second actuation cam.
 14. The machine according to claim 13,wherein said upper zing supports said cam and said at least onecomplementary cam; said complementary cam being movable with respect tosaid upper ring along said substantially radial direction with respectto the axis of the needle cylinder; said lower ring being arranged in adownward region and coaxially with respect to said upper ring and havinglocators supported thereon, which face an opposite side of saidcomplementary cam that is opposite with respect to a side that canengage the heel of the sinkers and are adapted to limit the movement ofsaid complementary cam along said radial direction away from the axis ofthe needle cylinder.
 15. The machine according to claim 13, comprisingelastic means that contrast movement of said complementary cam away fromthe axis of the needle cylinder.
 16. The machine according to claim 15,wherein said complementary cam has, on said opposite side thereof, aprofile that can engage said locators and is shaped so as to vary adistance of said profile from said locators when an angular position ofsaid lower ring with respect to said upper ring varies.
 17. The machineaccording to claim 13, wherein said first actuation means comprise afirst electric motor, supported by a fixed structure, said firstelectric motor being provided with an output shaft to which a firstactuation cam is keyed, said actuation cam being coupled to at least onecam follower that is connected to said upper ring of the sinker cover.18. The machine according to claim 17, comprising a pair of camfollowers, said first actuation cam being coupled to said pair of camfollowers, which are connected to said upper ring and are arranged so asto provide a bilateral and preloadable coupling with a profile of saidfirst actuation cam.
 19. The machine according to claim 18, wherein saidfirst actuation cam and/or said second actuation cam are provided so asto rotate about an axis that is parallel to the axis of the needlecylinder.
 20. The machine according to claim 19, wherein profileportions of said first actuation cam and/or of said second actuation camare shaped complementarily and are coupled, respectively, to said pairsof cam followers.
 21. The machine according to claim 17, wherein saidfirst and second electric motor of the actuation means is constituted bya step motor.
 22. The machine according to claim 20, comprising sensingmeans for sensing rotation of said first actuation earn and/or of saidsecond actuation cam about axis thereof.
 23. The machine according toclaim 22, comprising sensing means for sensing rotation of said upperring and/or of said lower ring of the sinker cover about the axis of theneedle cylinder.
 24. The machine according to claim 20, wherein theprofile of said first actuation cam and/or of said second actuation camis shaped so as to determine a linear relationship between a rotation ofsaid first actuation cam and a rotation of said upper ring of the sinkercover and/or between a rotation of said second actuation cam and arotation of said lower ring of the sinker cover.